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11.
Ralf Hollstein 《manuscripta mathematica》1977,22(1):7-12
It is known that the inductive tensor product of two barrelled spaces is barrelled and that the projective tensor product of two barrelled metrizable spaces or barrelled (DF)-spaces is barrelled. In this note it will be shown by a counterexample that the projective tensor product EF of two barrelled spaces E and F in general is not barrelled, even if E is (DF)-Montel-space and F (F)-Montel-space. Furthermore we show that the -tensor product of two (B)-spaces in general is not barrelled. It follows from the fact that an (F)-space E is nuclear if and only if the -tensor product E
l
4 is barrelled. 相似文献
12.
Ralf Eiden Ralf Falter Barbara Augustin-Castro Heinz Friedrich Schöler 《Analytical and bioanalytical chemistry》1997,357(4):439-441
Distillation as a way of sample digestion has been combined with on-line RP C18 preconcentration and HPLC-UV-PCO-CVAAS (high
performance liquid chromatography – ultra violet – post column oxidation – cold vapour atomic absorption spectrometry) for
the determination of methylmercury at background levels in sediments, soils and fish tissue. To prove the accuracy of this
method, it was applied to sediment and fish tissue reference materials. The results correspond with the reference values within
their error ranges. Excellent recoveries (92–95%) were obtained for the sediment samples by means of the standard addition
method. The standard deviations of the sediment samples were within an acceptable range (7.2–12.5%), those of the fish samples
were substantially lower (3.4–5.0%). The detection limit is 0.04 ng/g for 1 g sample weight.
Received: 23 November 1995/Revised: 16 April 1996/Accepted: 20 April 1996 相似文献
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A series of samples with the composition Ca(1)(-)(x)Na(2)(x)Al(2)B(2)O(7) (0 < x < or = 1) was investigated and a hexagonal structure with unusually large range of homogeneity (at least from x = 0.01 to 0.95) was revealed. The hexagonal phase consists of [Al(2)B(2)O(7)](infinity)(2)(-) lamellae stacked along the c axis, as in CaAl(2)B(2)O(7) and Na(2)Al(2)B(2)O(7). Nevertheless, the configuration and stacking sequence of the [Al(2)B(2)O(7)](infinity)(2)(-) lamellae are different in these three structures. In the hexagonal structure of Ca(1)(-)(x)()Na(2)(x)()Al(2)B(2)O(7), Ca and half Na cations (Na1) statistically occupy the same crystallographic site which is located between the [Al(2)B(2)O(7)](infinity)(2)(-) lamellae, the other half Na cations (Na2) distribute in the planes bisecting the [Al(2)B(2)O(7)](infinity)(2)(-) lamellae. Depending on the composition, the site occupation factor of Na2 site can vary in the same range as x, leading to a tunable density of Na(+) vacancies in the structure. The AlO(4) tetrahedra and BO(3) triangles in the structure tilt in appropriate ways to improve the bond valence sum of Na2 cations which are not sufficiently bonded to the anions. 相似文献
15.
Kevin D. Oliphant Marius Karger Yoichi Nakanishi Ralf R. Mendel 《Molecules (Basel, Switzerland)》2022,27(12)
Molybdenum (Mo) is an essential trace element in all kingdoms of life. Mo is bioavailable as the oxyanion molybdate and gains biological activity in eukaryotes when bound to molybdopterin, forming the molybdenum cofactor. The imbalance of molybdate homeostasis results in growth deficiencies or toxic symptoms within plants, fungi and animals. Recently, fluorescence resonance energy transfer (FRET) methods have emerged, monitoring cellular and subcellular molybdate distribution dynamics using a genetically encoded molybdate-specific FRET nanosensor, named MolyProbe. Here, we show that the MolyProbe system is a fast and reliable in vitro assay for quantitative molybdate determination. We added a Strep-TagII affinity tag to the MolyProbe protein for quick and easy purification. This MolyProbe is highly stable, resistant to freezing and can be stored for several weeks at 4 °C. Furthermore, the molybdate sensitivity of the assay peaked at low nM levels. Additionally, The MolyProbe was applied in vitro for quantitative molybdate determination in cell extracts of the plant Arabidopsis thaliana, the fungus Neurospora crassa and the yeast Saccharomyces cerevisiae. Our results show the functionality of the Arabidopsis thaliana molybdate transporter MOT1.1 and indicate that FRET-based molybdate detection is an excellent tool for measuring bioavailable Mo. 相似文献
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Thomas Höche † Peter A. van Aken Michael Grodzicki Frank Heyroth Ralf Keding Reinhard Uecker 《哲学杂志》2013,93(29):3117-3132
Based on cluster molecular orbital calculations, high-energy resolution (ΔE?~ 0.4?eV) Ti–L2,3 electron energy loss near-edge structures of single-crystalline and glassy Ba2TiGe2O8 are interpreted. The finding that the Ti–L2,3 near-edge structure of the Ba2TiGe2O8 single crystal possesses less pronounced peaks than the glass under identical experimental conditions can be attributed to distinct distortions of the titanium environment caused by the very strong one-dimensional structural modulation hosted by the Ba2TiGe2O8 crystal lattice. As lattice periodicity is absent in the glass, the titanium environment is more regular in the vitreous surroundings. Moreover, the modulation in crystalline Ba2TiGe2O8 is responsible for the virtually indiscernible O–K near-edge structures of the glassy and crystalline samples. 相似文献
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